King Tutankhamun Posted April 7, 2004 Report Share Posted April 7, 2004 Wooooza! That is impressive Mark. Is that right Dnas? Quote Link to comment Share on other sites More sharing options...
Dnas Posted April 7, 2004 Report Share Posted April 7, 2004 Yup. Quote Link to comment Share on other sites More sharing options...
MarkT Posted April 8, 2004 Report Share Posted April 8, 2004 Solve simultaneously:3a + b - c =10,a - 2b + 3c = -7,2a + 3b - 2c = 15a = ?, b = ?, c = ?Bonus points for solving it via a matrix method. Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 9, 2004 Report Share Posted April 9, 2004 a=2,b=23-10a=3c=13 -7a =-1 Quote Link to comment Share on other sites More sharing options...
Jeru Posted April 9, 2004 Report Share Posted April 9, 2004 Got the same results.Never heard of the matrix method. Quote Link to comment Share on other sites More sharing options...
Dnas Posted April 10, 2004 Report Share Posted April 10, 2004 The matrix method is putting it in reduced row echelon form. Search on Google for it or something. Quote Link to comment Share on other sites More sharing options...
MarkT Posted April 11, 2004 Report Share Posted April 11, 2004 Yes, correct. Quote Link to comment Share on other sites More sharing options...
Argalius Posted April 12, 2004 Report Share Posted April 12, 2004 The matrix methodIs that simple math?!?! Quote Link to comment Share on other sites More sharing options...
MarkT Posted April 12, 2004 Report Share Posted April 12, 2004 The matrix methodIs that simple math?!?! Relatively speaking... Quote Link to comment Share on other sites More sharing options...
av_nefardec Posted April 12, 2004 Report Share Posted April 12, 2004 Never heard of the matrix method. The matrix method is putting it in reduced row echelon form. Search on Google for it or something.Well to search it I'd tell you to look for Gauss-Jordan Elimination - that's the actual method used.But you could also invert the coefficient matrix and multply it by the matrix each equation equals.3a + b - c =10,a - 2b + 3c = -7,2a + 3b - 2c = 15[3 Â 1 Â -1]^-1 Â Â Â Â Â [10] Â Â Â Â Â Â Â Â Â Â [a][1 Â -2 Â 3] Â Â Â Â * Â Â [-7] Â Â Â Â = Â Â Â Â Â [b][2 Â 3 Â -2] Â Â Â Â Â Â Â [15] Â Â Â Â Â Â Â Â Â Â Â [c]This should give you the answers you need. The only problem is inverting the 3x3 matrix, which is usually a pain to do by hand.*waves his calculator about in the air* Quote Link to comment Share on other sites More sharing options...
Argalius Posted April 13, 2004 Report Share Posted April 13, 2004 Really ... euhh ... interesting. Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 15, 2004 Report Share Posted April 15, 2004 I still don't understand. Quote Link to comment Share on other sites More sharing options...
Argalius Posted April 15, 2004 Report Share Posted April 15, 2004 Does anyone have a new problem yet? Quote Link to comment Share on other sites More sharing options...
CodeOptimist Posted April 15, 2004 Author Report Share Posted April 15, 2004 Here's a simple problem:Solve these equations using substitution:2y - 3x = 2y + 2x = 5 Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 16, 2004 Report Share Posted April 16, 2004 2y - 3x = 2 and 2y + 4x = 10 are given--> 2y - 3x - (2y + 4x) = 2 -10--> 7x = 8--> x = 8/7------------------------OR--------------------------------2y - 3x = 2 and y = 5 - 2x--> 2*(5-2x) - 3x = 2--> 10 - 7x = 2--> x = 8/7 Quote Link to comment Share on other sites More sharing options...
MarkT Posted April 17, 2004 Report Share Posted April 17, 2004 Give a formula for the area of a regular (perfect) hexagon in terms of the length of one of the sides. Quote Link to comment Share on other sites More sharing options...
Sam Posted April 17, 2004 Report Share Posted April 17, 2004 ooh ooh I know this oneSL2 / 4{tan(180/S)}S=sides and L=side lengths(assuming that they would be the same)Did I get it right? Quote Link to comment Share on other sites More sharing options...
MarkT Posted April 17, 2004 Report Share Posted April 17, 2004 Not the question I actually asked, but yes, that's correct.(Fitting 6 into that formula gives (3/2).sqrt(3).L^2, for a hexagon) Quote Link to comment Share on other sites More sharing options...
Jeru Posted April 17, 2004 Report Share Posted April 17, 2004 Btw, Bob, I was always taught that one needs to find both x and y. Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 18, 2004 Report Share Posted April 18, 2004 that's right. but when I have x I can get y very easily (you know 2y-3x=2 and x=8/7)or have you meant that you thaught you need two different x's and y's? Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 21, 2004 Report Share Posted April 21, 2004 new question:a^2 + b^2 = -103a - b = 0not sure whether it's possible to answer or whether there is only one possibility Quote Link to comment Share on other sites More sharing options...
DarkAngelBGE Posted April 21, 2004 Report Share Posted April 21, 2004 a^2 + b^2 = -10LOL Good luck everybody finding the solution. :P Quote Link to comment Share on other sites More sharing options...
Mystic-Al-Bob Posted April 21, 2004 Report Share Posted April 21, 2004 maybe there are some complex numbers in the solution?! Quote Link to comment Share on other sites More sharing options...
Klaas Posted April 21, 2004 Report Share Posted April 21, 2004 I don't think that's possible Edit:Oh complex numbers...can't remember how to work with those anymore Quote Link to comment Share on other sites More sharing options...
DarkAngelBGE Posted April 22, 2004 Report Share Posted April 22, 2004 AH yeah complex numbers. SHould have said that, Bob. I will try my hand this afternoon, gotta go to school now. Quote Link to comment Share on other sites More sharing options...
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